1. Field of the Invention
This invention relates to a print job control system that is linked to a local area network (LAN) or other communications information networks for efficient processing of print requests generated from a plurality of workstations.
2. Discussion of the Related Art
LANs and other communications information networks (hereinafter referred to simply as "networks") generally have a plurality of workstations, file servers, terminals, facsimile machines and various servers linked thereto, as well as a print server which controls the print job using a processor in the execution of various print jobs (the print server is hereinafter referred to as a "printer").
The essential part of a network of the type contemplated by the present invention is shown schematically in FIG. 9, in which the network generally indicated by 10 has linked thereto various servers including a plurality of workstations 11 (11-1, 11-2, . . . 11-n), a printer 12, a facsimile 13 and a file server 14.
While many workstations generating print jobs are usually linked to the network, a smaller number of printers 12 are used and, in a typical case, a single printer is used with several workstations. In order to execute print jobs generated from a plurality of workstations 11 in a predetermined order, the print job control processor builds a print queue table containing all queue identifiers necessary to identify the print jobs to be executed, and the specific printing of jobs is performed in accordance with the print queue table.
Prior print job control systems have the capability of automatically changing the order of queue identifiers in the print queue table in accordance with the specific sort option designated by the operator. When this system receives a new print job, the queue identifier of the print job is inserted into the print queue at an appropriate position in accordance with the sort option designated by the operator. The system is so designed that in the absence of a designated sort option, the operator is free to rearrange certain queue identifiers in the print queue table. If a particular sort option is designated by the operator, the system will disregard the position of the queue identifier for the operator-designated print job in the print queue table and rearrange queue identifiers in the order that complies with the particular designated sort option.
In typical prior art systems the following four sort options (1)-(4) may be designated by the operator:
(1) print requests are sorted according to the time they are entered (First-in First-out, or FIFO);
(2) the queue identifier for the print job that requires binding is inserted at the top of the print queue table (Binder First);
(3) print requests are sorted according to the requested time of printing (Short Job First); and
(4) the media (printing media ) required in a particular print job are compared with the media loaded in the printer and the queue identifier of a print Job which is such that all the media it requires are loaded (e.g., a print job that uses a plurality of media to print graphs on OHP sheets and sentences on sheets of plain paper to create a report containing the graphs) and is inserted at the top of the print queue table (Stack Match).
While the prior art of the kind outlined above is described in many books, "Local Area Networks" ed. by Akihiro Kamiya and published by Maruzen, pp. 229-256 is cited as a typical reference.
In the prior art outlined above, the operator can change the order of queue identifiers on the print queue table only when he has not designated a sort option. If he wants to execute an urgent print job, he must first cancel the currently operating sort option before changing the order of queue identifiers on the print queue table (by inserting the queue identifier of the urgent print .job at the head of the print queue table). These procedures are unsuitable for rapidly processing documents that must be urgently printed out.
A further problem with the prior art occurs with the four sort options described above, since a print job that is located toward the end of the print queue table will never be executed as long as a higher-priority print request is accepted.